I just got my G1 yesterday. I stayed up most of the night playing with it. I am coming from BlackBerry (8830, 8330, 9530). So far, I am very impressed with it. I love how I have access to all of my email folders right from the email app. I have so much to learn about this phone. But it's fun to me. So, I guess I will be doing a lot of reading on the forum for the next few days.
BTW: I am just blown away by the number of apps available for the G1. And the fact that the vast majority of them are free, makes it all the sweeter.